I have been testing out a Perkeo 6x6 folding camera. At infinity setting I am getting the center of the negative sharply focused. However, the left side is blurry. See example attachment. This fuzziness is less apparent in shots focused 60 ft or less. I have tried measuring the parallelism of the lens and the back film rollers and, within my accuracy limits, they seem OK. The lenses are clean and very clear. Any suggestions?